This invention relates to subzero refrigeration and cooling systems using compressed air as a coolant instead of environment-damaging and expensive systems using freon, liquid nitrogen, ammonia or other substances.
The inventor was experimenting with the air-based refrigerating devices for more than thirty years. This honing and fine tuning process has resulted in the present invention. The prior art is replete with refrigeration devices employing air for heat transfer. For example, U.S. Pat. No. 5,438,845 by Kirschner et al. discloses a refrigeration device with compressed and turbo expanded air based on a venturi-like ejector circulating the refrigerant within the refrigeration chamber.
U.S. Pat. No. 4,430,867 by Warner disclosed an air cycle refrigeration system for aircraft cabins including a sink and circulation heat exchangers for melting ice in the exhaust air and exhaust air from the system""s turbine.
U.S. Pat. No. 5,718,116 by Grassi at al. disclosed an open loop, air refrigerant, heat pump process for a food freezer employing cold expander discharge to cool air feed to the expander prior to suing this portion as a regeneration gas for adsorbent-containing drier.
U.S. Pat. No. 4,829,775 by Defrancesco disclosed an air-conditioning system with a filter of compressed air coming from a heater and passing through a second re-heater downstream of the filter and upstream of the turbine for maximizing efficiency of the turbine.
U.S. Pat. No. 5,699,672 by Foerster et al. revealed a refrigeration apparatus and method in which compressed air is subjected to isothermal compression in a water-injected screwtype compressor with subsequent adiabatic and isentropic expansion in a high-speed turbine.
U.S. Pat. No. 5,921,093 by Jonqueres disclosed an air cycle system using a re-heater condensing water vapor extracted from compressed air and then cooled by a sub-cooler heat exchanger and re-heated in the re-heater condenser before its expansion in a turbine for enclosure conditioning.
However, none of the prior art references known to the inventor discloses the present invention shown and described herein.
A novel system and method employing compressed air as primary refrigerant dramatically reduces exploitation cost, increases efficiency and produces pollution-free discharge in contradistinction with existing systems using freon, liquid nitrogen or other chemical substances. Compressed air travels through three dehumidifying steps including a passage through a pre-cooler for initial dehumidification, moisture separator, and dryers regenerated by independent heaters or system exhaust air drying off the moisture-absorbing material. Then, the air travels through a dust filter, turbine expander, refrigeration chamber with a sinusoidal path channel, impeller fan, heat exchanger and a noise-attenuating muffler. The unique design resolves technical problems previously preventing mass production of noise-free and inexpensive air-based refrigeration systems.